The present invention relates to an image recording apparatus to record an image on a silver halide color photosensitive material with the use of recording elements which emit a light in accordance with image data.
Conventionally, there has been a technique to record a color image on a silver halide color photosensitive material with the use of various single light source elements or light source elements aligned in a form of an array (hereinafter referred to as to an array-like light source).
A device disclosed in Japanese Patent Application Open to Public Inspection No. 62-134624 in which a back light and a liquid crystal shutter array are combined, and a device called a VFPH (vacuum fluorescent print head) which uses a printing head having a vacuum fluorescent tube light source have been proposed. The vacuum fluorescent tube light source has an easily obtainable high luminance, a high responding ability and a thin type. As the phosphor, an oxidized zinc phosphor (ZnO:Zn) is selected for durability.
LED light source is used as a light source in the electrophotography. In the LED light source, a high density array of 300 dpi or 400 dpi can be manufactured for red by a photomask method. However, for blue and green, the LED array can not be produced at present by the same method as that for red.
Further, among the abovementioned light sources, the liquid crystal shutter array is not suitable for use in high speed recording because of a relatively slow responding speed.
On the other hand, with regard to LED for green and blue, it is difficult to obtain them at a low cost, even in a form of a single element light source. Further, an array-like light source may be made in such a way that the single elements are arranged in an array form. However, with such an arrangement, the mounting density of the elements may be lowered. Accordingly, the resolution of the output image formed by it may be also lowered with the lowered mounting density, causing a problem of image quality degradation. For this problem, a technique to improve the resolution by the use of a reducing optical device may be considered. However, such a technique raises other problems because that the apparatus becomes large in size and manufacturing cost is increased.
Furthermore, the wavelength of the light emitted by the VFPH using the oxidized zinc phosphor (ZnO:Zn) shows a curve which has a peak around 500 nm and widens broadly from the peak point. Therefore, since the light is easily separated into three color lights of blue, green and red, the exposure for color instant film has been conducted by a method using this technique.
However, when the exposure for a silver halide color photosensitive material, in particular, for a color paper (hereinafter referred to as to a printing paper) is conducted with the above method, since an amount of red light is insufficient, the exposure inevitably takes a long time, problem causing the of preventing the image recording at high speed.
For this problem, changing of the components of the phosphor could be considered to improve the sensitivity for red. However, the change raises another problem in that the life span of the phosphor becomes short, resulting in an increase of the running cost.